Sound-reproducing machine



R. MOSMANN. SOUND REPRODUCING MACHINE.

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n/zar fi/asmda v Q 1 Maw Patented Dec. 12, 1922.

UNITED STATES 1,438,712 PATENT OFFICE.

BEINHAR-D MOSMANN, OF S'l. GALLEN, SWITZERLAND.

SOUND-REPRODUCING MACHINE.

Application filed March 1, 1922. Serial No. 540,235.

To all whom it may cont-cm:

Be known that I, REINHARD MosirANN, a citizen of Switzerland, and residing at St. Gallen, Switzerland, have invented cer-,

cabinet type, and it relates more specifically to improvements in means for modulating and amplifying the sound waves passing from the sound box through a sound conveyer, which includes the tone arm and horn, to the mouth of the latter, and the particular object of the invention is to provide an improved. and novel type of sound controller and amplifier and to so mount the modulator and freely suspend this amplifier within the sound conveyer that the sound waves can readily be controlled as to their intensity, and that motor and other disturbing sounds and noises are not transmitted to the emitted from the horn, as is apt to be the case where the sounding boards of other types of amplifiers are in rigid contact with the walls of the machine casing or the sound conveyer.

The construction and arrangement of the parts of my invention is such that the tone quality is not in any way interfered with by foreign noises propagated in the main casing and the sound conveyer or horn, but that only the actual wanted sound waves emanating from the sound box are caused to impingely act upon the resonator parts and are thereby amplified and in this state issue from the resonance chamber.

My invention will best be understood when described in connection with the accompanying drawing, in which Fig. 1 is a vertical longitudinal section through a preferred embodiment of the invention, of which Fig. 2 shows a front view and Fig. 3 a. plan. Fig. i is a vertical section through the modulator or damper, of which Fig. 4 is a plan view. Fig. 5 is a front View of the amplifier proper, partly in section, and Figs. 6 and 7 respectively are longitudinal section and front elevation of a modification.

The tapering sound conveyor 0r horn 1, which is secured to the cabinet wall 4 by screws 5 passing through its rigid fastening plate 2 and an interposed sound-deadening amplifier and then pad 3, may be. of any conventional shape; as shown by wayof example it is of gradually tapering conformation with square corners, but it may, obviously, also be of round, oval, or other cross-section. The attenuated upper end communicates with the tone arm support 6. In the wide forepart of the horn is suitably suspended from the top wall 7 the amplifier A. This latter, by way of example, comprises a top plate 10 and a bottom plate 1.0 interconnected at the corners by posts 9 and kept under stress in bow-shape by the interposed distance rod 11 with their concave surfaces in juxtaposition; The upper sound plate 10 carries a rib 8 by which the device is secured to the horn wall in any suitable manner, for instance by means of the screws 8, a soundabsorbing pad 8 being interposed, as shown in Fig. 5.

Midway between these two sound plates 10 and 10 is suspended. by the rod 11 a resonance board 12 provided with relatively large corner perforations 13 for the free passage of the posts 9. The plates together form a circumferentially open. subdivided resonance chamber and for their manufacture the best quality of resonance wood is chosen, such as is used for violins and like instruments. The middle plate 12 does not contact anywhere except in the centre at the point of suspension, and the plates 10 and 1C are concavely facingly flexed and stressed as described and shown. To the rear edge of the intermediate plate 12 there is secured at 14 the one end of a carrier arm 15, which is bent to follow the curvature of the sound duct and whose upper end supports the dished sound receiving and transmitting disc 16. This latter, which hereinafter will be referred to as sound transmitter, is only very slightly smaller in diameter than the horn crossscction at this point and is not in contact therewith in any way, and it thus directly receives by far the major part of the sound waves sent out by the needle-vibrated diaphragm and then transmits these sound vibrations over the Z3 middle one in the soundduct the modulator or damper 17:, in the shape of a hinge flap of rigid material, iulcrumed in the horn Wall and its "fulcrum pin 18 extending through the Wall,

as shown in F 2. By manipulation of this pin in any suitable manner, direct special connections not shown here,

'1'? operating in a prisn atic neck 22, which arrangement allows of employing a relatively large resonance chamber with correspondingly enhanced sound volume over the conventional taperin horn const actions.

in use the sou d ares with the modulaopen, Will practically all directly impin ;e on the sound disc 16 (or 20 in Fig. 6) which Will then transmit them to the amplifi r f Whose parts Will be caused to vihratc T Then pass on the amplified Waves without admixture of disturbing foreign sounds out of the mouth oi the horn. On the modulator being); closed more or less the sound WSWGS first impinge upon this iviil obstruction and will then be propagated in correspondr y damped intensity to the disc 16 so that by manipulating the modulator flap the tone strength cont-rolled Without interiering with the amplifier operation.

lihat I claim is .l. in a sound reproducing machine inding a sound conveyeig an amplifier in aid conveyor comprising a plurality of pacodiy "nerconnected sound boards, and sound transmitter rigidly spacedly convetcd to one or said sound boards.

2. in sound reproducing machine; including a sound coirveyer an amplifier presenting subdivided, circumferentially open resonance chamber, and sound transmitter in rigid association with said amplifier and 2 id sound transmitter having; a diameter to practically occlude said sound conveyor withoirt hoircwer contacting therewith.

3. a sound reproducing machine inc uding; a sound conveyor an amplifier in said conveyer con'iprising three spacedly horizontally superposech interconnected sound boards and a sound transmitter in 1 id con ection with, but spaced. from, the

of said sound boards.

*an readily he 4:, in a sound reproducing machine inv Ll t a. Mi 7 u r lu ing i sound "cave; er, n amplriei in said sound conveyor and comorisin a tco & 1 b l,

resonance plate, bottom resonance plate, intermediate resonance plate, all

i (vii spacedly interconnected in substantially horizontal relative arrangementa sound transmitter in said sound conveyor, and a rigid distance conn ction. between said interclu mg a sound conveyer an amplifier coniprlsing top )late, bottom plate, and an intermediate pi te, all or resonant character. means coi'ne vise connecting said top and bottom platen means for stressing said top and bottom places in opposite sense and for suspending sail i termediate plate between them out or contact therewith except at a central point, and a sound transmitter in rigid connection witln but spaced from, said intermediate plate.

7. in a sound reproducing machine including a sound conveyer, in con'ihination, an amplifier comprising; a top resonator pi and a. bottom resonator plate means r1 idly connecting said plates near their ciicuinference and a central distance meml'ier For respectively outivariilly flexing; and stressing said two resonator plates, an unflened resonator plate freely suspended inter at a 'ngrle e said two tie plates 'al point by said L.- o having perforations for he i L contacting with said sound conveyer only at a single point of connection, a sound l i r in the contracted portion of said sound conveyen and means for rin'idl necti i sound transmitter to said mediate untlexed resonator pl in testimony whereof l allii; my signature.

nnnuiann MOSMANN.

y con- 1nter- 

